Author name code: neckel ADS astronomy entries on 2022-09-14 author:"Neckel, Heinz" ------------------------------------------------------------------------ Title: Analytical Reference Functions F(λ) for the Sun's Limb Darkening and Its Absolute Continuum Intensities (λλ 300 to 1100 m) Authors: Neckel, Heinz Bibcode: 2005SoPh..229...13N Altcode: It is shown (1) that the coefficients Ai of the limb darkening functions I(μ)/Icenter = P5 (μ) = ∑Ai μi (i = 0... 5; μ = cos ϑ), which had been published by Neckel and Labs (Solar Phys.153, 91, 1994), can well be approximated by analytical functions of wavelength λ, and (2) that at first sight purely formal extrapolation of the functions P5(μ) to the very limb (μ = 0.0) is not meaningless: in combination with absolute intensities for the disk center these functions yield `limb intensities' which all correspond to almost the same `limb temperature', Tlimb≈4746 K. Together these results lead to `reference functions' which can quickly yield rather reliable values of the Sun's continuum intensities, for any values of μ and λ. Title: On the sun's absolute disk-center and mean disk intensities, its limb darkening, and its `limb temperature' (λλ330 to 1099 nm) Authors: Neckel, Heinz Bibcode: 2003SoPh..212..239N Altcode: The coefficients A0 of the limb-darkening functions I(μ)/Icenter=P5(μ)=ΣAiμi (i=0,...5, μ=cos θ), published by Neckel and Labs (1994), and the corresponding disk-center intensities Icenter=I(μ=1), which were taken from the absolutely calibrated Kitt Peak FTS Atlas of the disk center (Brault et al., see Neckel and Labs, 1984, and Neckel 1999), are used to derive `limb intensities' Ilimb=I(μ=0)=A0Icenter. The corresponding `limb temperatures' Tlimb vary only slightly with wavelength; the mean value (≃4750 K) and the wavelength of maximum intensity (≃605 nm) conform to Wien's law (λmaxT=0.288 cm K). Further, Tlimb agrees closely with that temperature, which follows from Avrett's (2000) model of the photosphere for τ500≃0.006; for this layer the optical thickness along the line of sight is close to 1 (`the limb'; compare Unsöld, 1968). The slight variation of Tlimb with wavelength is presumably due to systematic errors in the Neckel and Labs intensity data: it corresponds almost precisely to the differences between their data and the more recent ones provided by, e.g., Burlov-Vasiljev, Gurtovenko, and Matvejev (1995), and Burlov-Vasiljev, Matvejev, and Vasiljeva (1998). Two simple correction functions (for λ≦550 nm and λ≧550 nm) are proposed, which apply to all Neckel and Labs intensity data (disk center and full disk, line spectrum and (quasi) continuum), and to the absolutely calibrated Kitt-Peak FTS Atlas (spectra of disk center and full disk) as well. Title: Solar Photosphere: Center-to-limb Variation Authors: Neckel, H. Bibcode: 2001eaa..bookE2012N Altcode: Many phenomena which are observable on the Sun's `surface' change in characteristic ways between the center and LIMB of the apparent disk (e.g. the shapes of sunspots, the profiles of Fraunhofer lines, etc). The most obvious and easily noticeable (e.g. at sunrise or sunset, or on a good photograph) center-to-limb variation is the decrease of brightness from the disk center ... Title: Alfred Bohrmann (28. Februar 1904 - 4. Januar 2000). Authors: Neckel, H. Bibcode: 2000MitAG..83....5N Altcode: No abstract at ADS Title: Announcement Authors: Neckel, H. Bibcode: 1999SoPh..184..421N Altcode: Announcement of the on-line availability of a digital atlas of the solar disk-center intensity spectrum and the disk-averaged flux spectrum, both based on observations with the Fourier Transform Spectrometer at the McMath-Pierce telescope at Kitt Peak by Brault and Testerman and calibrated to absolute intensity units following the analyses of Labs and Neckel. Title: On the Wavelength Dependency (and its Variations) of the Ratio Disk-Averaged to Disk-Center Intensity, F/I0 (λλ0.385 to 10 µm) Authors: Neckel, Heinz Bibcode: 1997SoPh..171..257N Altcode: In the whole wavelength range, 0.385 to 10.0 µm, the ratios F/I0 of disk-averaged intensity F to disk-center intensity I0 follow very closely the simple relation F/I0 = 0.975 - 0.091λ-1 - 0.00024λ-5. The residuals exhibit a well-defined structure with minima and maxima in the order of± 5 × 10-3 , which reflect the wavelength-dependency of the source function B(λ,τ) and the continuous absorption coefficient . The fact that the scatter of the coefficients of the relevant limb-darkening functions is usually much larger than the scatter of the F/I0 ratios seems to confirm the occurrence of limb-darkening variations, which however leave the F/I0 ratios almost unchanged. Nevertheless, minor differences between different observations, which concern the details in the wavelength-dependency of the F/I0 residuals, seem to indicate that even the F/I0 ratios undergo minor variations. Title: On the consistency of solar limb darkening observations at UV wavelengths (2000-3300A). Authors: Greve, A.; Neckel, H. Bibcode: 1996A&AS..120...35G Altcode: Limb darkening observations are important for the construction and verification of solar model atmospheres. We investigate the consistency of solar limb darkening data, published for the UV wavelength region between 2000 and 3300A, from the comparison of F/I_0_ ratios based either on direct limb darkening observations or on absolute irradiance (F) and disk-center intensity (I_0_) measurements. There exists a discrepancy between the limb darkening data of Moe & Milone (1978ApJ...226..301M) and other, direct or indirect, limb darkening observations. Title: On the wavelength dependency of solar limb darkening (λλ303 to 1099 nm) Authors: Neckel, Heinz Bibcode: 1996SoPh..167....9N Altcode: The limb-darkening data published by Neckel and Labs (1994) (5th-order polynomials P5(μ), μ = cos θ) are used to represent the limb darkening by the functions Ln(μ), proposed first by Kourganoff (1949a). When plotted against wavelength, the coefficients of these functions show a rather low scatter and appear to be linear functions of either λ−1 or λ#x2212;5. Title: A study of solar analogues in the ultraviolet. Authors: Fernley, J.; Neckel, H.; Solano, E.; Wamsteker, W. Bibcode: 1996A&A...311..245F Altcode: We have made a comparative study of the Sun and solar analogue stars using the published solar ultraviolet fluxes and IUE low dispersion spectra of the solar analogues. The Hyades dwarf HD 28099 (vB64) shows a flux excess below 2500A which is probably due to chromospheric activity since it is a relatively young star. HD 44594, 186408 (16CygA) and 186427 (16CygB) all show very similar ultraviolet spectra to the Sun. From a comparison with Kurucz ATLAS9 models we find 16CygA and B to be metal-rich by 0.02+/-0.03dex with temperatures of 5790+/-20K and 5750+/-20K respectively, assuming a solar temperature of 5770K. These results are consistent with other recent work. For HD 44594 we find T_e_=5760+/-20K and [M/H]=0.01+/-0.03 which is significantly less metal-rich than found in the recent work of Cayrel de Strobel & Bentolila (1989). We have also checked the ultraviolet absolute flux scale by comparing the ratio of the solar analogue fluxes to the solar flux at both optical and ultraviolet wavelengths. For 16CygA and B we find that, after normalising in the optical and using the ATLAS9 models to correct the ultraviolet fluxes of the solar analogues for their small metallicity excess, there is a discrepancy of 16(+/-4)% in the sense that the IUE absolute calibration gives fluxes that are too low or the absolute scale of the solar uv flux measurements is too high. This can be reduced to 6(+/-4)% if we firstly accept a 7% higher IUE absolute scale as suggested by independent evidence, and secondly use only the older solar ultraviolet flux measurements of Heath (1980) & Mentall et al. (1981) and ignore the more recent work of Labs et al. (1987). Finally we have inverted the problem and asked which of the three solar flux measurements (Heath, Mentall et al. or Labs et al.) fit better the slope of the ultraviolet continuum of the solar analogue IUE data. As with the absolute scale we find better agreement with the older measurements of Heath and Mentall et al. than with the more recent work of Labs et al. Title: On the Relation between the Sun's (Geocentric) Angular Diameter and the Observed (Topocentric) `Drift Time' Authors: Wittmann, Axel D.; Neckel, Heinz Bibcode: 1996SoPh..163....1W Altcode: It is pointed out that the relation between the Sun's geocentric diameter and the so-called drift time observed on the Earth's surface does not depend on topocentric data (distance, declination, parallax, refraction), but only on the geocentric values of distance, declination, and variation of right ascension. Title: The Solar Radius Derived from Limb-Darkening Scans Obtained in 1981 and from 1986 to 1990 Authors: Neckel, Heinz Bibcode: 1995SoPh..156....7N Altcode: Solar-radius data are presented which result from observations made in 1981 and from 1986 to 1990. These data, which are a by-product of the limb-darkening observations made by Neckel and Labs (1984, 1994), do not show significant deviations from the value which is adopted from Auwers (1891) for computations of solar eclipses and of the Sun's ephemeris in theAstronomical Almanac. Title: Solar Limb Darkening 1986-1990 Lambda 303-NANOMETERS to 1099-NANOMETERS Authors: Neckel, Heinz; Labs, Dietrich Bibcode: 1994SoPh..153...91N Altcode: The Sun's limb darkening was observed repeatedly between the 1986 minimum and the 1990 maximum of solar activity.Systematic variations, which could depend either on the momentary activity and/or the phase in the solar cycle, werenot detectable, either at continuum wavelengths or in two broad-band spectral intervals. Completelyirregular variations, which concern not only individual, successive scans (due to granulation, etc.), but also thedaily andseasonal averages, are usually less than 1%, but can reach occasionally 2% or even more. Minoreast-west asymmetries even in the seasonal means seem to be well established, mainly for λ < 400 nm. Thefinal, mean limb-darkening coefficients agree basically with those published by Pierce and Slaughter (1977) and Pierce, Slaughter, and Weinberger (1977), but show a much lower scatter when plotted against wavelength. Title: Solar Absolute Reference Spectrum Authors: Neckel, H. Bibcode: 1994svsp.coll...37N Altcode: 1994IAUCo.143P..37N No abstract at ADS Title: Variations of `wavelengths' and `bisector indices' of 70 solar spectral lines between 3300 and 3960 Å in Kitt Peak FTS spectra Authors: Neckel, Heinz; Labs, Dietrich Bibcode: 1990SoPh..126..207N Altcode: Wavelengths and bisector indices (a special measure for the asymmetry of a line near its bottom) are determined for 70 lines in each of 47 high-dispersion spectra. The spectra were obtained with the Fourier Transform Spectrograph connected to the McMath Telescope at Kitt Peak National Observatory; they all cover the same spectral range from 3200 to 4000 Å and concern either the full disk (19 `disk' spectra), or the disk center (9 `center' spectra), or two areas at sin ϑ = 0.85 on the west- and east-side of the disk (19 `limb' spectra). The main observing seasons were June 1986, June 1987, April and June/July 1988. The - relative - position of an individual line in one spectrum can be established with a precision of about 4 m s-1, the precision of one bisector index is 1-2 m s-1. Title: The role of telescopic stray light in limb-darkening scans obtained in April 1981 (and later) Authors: Neckel, Heinz; Labs, Dietrich Bibcode: 1990SoPh..126...47N Altcode: The suspicion of Elste (1990), that telescopic stray light together with imperfect collimation of telescope and spectrograph could be a possible explanation for the systematic differences and variations found by Neckel and Labs (1987) in many limb-darkening scans, proves to be unfounded for the following reasons: (1)The collimation was performed very precisely; (2) the telescope mirrors remained fixed in position and direction during most of the observing period; (3) stray light effects depending on hour angle were not detectable; (4) in the same collimation status, also many almost symmetric scans had been recorded; (5) the observed east-west differences in the solar intensities are partly even larger than the total amount of stray light (from telescope and sky!) observed as `sky'-background just outside the limb; (6) any east-west differences in the `sky'-background near the limb are just a few 0.01% of the disk center intensity; (7) the differences of the average intensities along eastern and western radius appear to be correlated with the east-west differences of the intensity's R.M.S. Title: Pennäler-Astronomie in verrückter Zeit. Authors: Neckel, H. Bibcode: 1989S&W....28..296N Altcode: No abstract at ADS Title: Multiplier hysteresis and image motion errors in limb darkening scans obtained in April 1981 (and later) Authors: Neckel, Heinz; Labs, Dietrich Bibcode: 1989SoPh..120..205N Altcode: In response to the comment of P. Foukal (1989) we show that in our limb darkening observations multiplier hysteresis and image motion (seeing) can be ruled out as major sources of error. Title: SYSTEMATIC OBSERVATIONS OF THE SUN (In honour of Helen Dodson Prince): Observations Authors: McIntosh, P.; Snodgrass, H.; Mouradian, Z.; Harvey, K.; Altrock, R.; Simon, P.; Legrand, J. -P.; Alissandrakis, G.; Neckel, H.; Petropoulos, P.; Poulakis, X.; Gokhale, M. H.; Sivaraman, K. R.; Pap, J. Bibcode: 1989HiA.....8..672M Altcode: No abstract at ADS Title: Asymmetry and Variations of Solar Limb Darkening Authors: Neckel, H.; Labs, D. Bibcode: 1988srov.proc..201N Altcode: No abstract at ADS Title: Ultraviolet Solar Irradiance Measurement from 200-NM to 358-NM during SPACELAB-1 Mission Authors: Labs, D.; Neckel, H.; Simon, P. C.; Thuillier, G. Bibcode: 1987SoPh..107..203L Altcode: The paper presents the results obtained from the UV-spectrometer of the `Solar Spectrum Experiment' during the Spacelab 1 mission in December 1983. The irradiance data concern 492 passbands, which are located between 200 and 358 nm at almost equidistant wavelengths separated by about 0.3 nm. The passbands have a well-defined, bell-shaped profile with a full width at half maximum of about 1.3 nm. The data, which have an error budget between 4 and 5%, agree closely with the spectral distributions observed by Heath (1980) and Mentall et al. (1981) and confirm that the solar irradiance and the fluxes of Sun-like stars show about the same spectral distribution down to at least 240 nm. Title: Erratum - the Bright Stars with Ubv-Colors Close to those of the Sun Authors: Neckel, H. Bibcode: 1987A&A...176..372N Altcode: No abstract at ADS Title: Asymmetry and variations of solar limb darkening along the diameter defined by diurnal motion in April 1981 Authors: Neckel, Heinz; Labs, Dietrich Bibcode: 1987SoPh..110..139N Altcode: Unexpected asymmetries and variations, which showed up in the first, preliminary reductions of new limb-darkening observations made in June 1986, near the present minimum of solar activity, stimulated a re-analysis of our limb-darkening observations made in April 1981 at Kitt Peak (Neckel and Labs, 1984). The results seem to indicate rather definitely that the intensity distribution across the disk varies at all observed wavelengths between 3300 and 6600 Å with amplitudes in the order of 1-2 % and time-scales from minutes to hours. Asymmetries in the intensity distribution with respect to the disk center are a frequent phenomenon. There can be no doubt, that also the absolute disk center intensity undergoes variations with comparable size and modulation, as they were in fact recently observed by Koutchmy and Lebecq (1986). Presumably, the solar oscillations contribute a significant part to the observed effects. However, due to the 5-7 min periodicity of our observations no definite conclusions can be drawn. Title: Ultraviolet solar irradiance measurement from 200 to 358 NM during Spacelab 1 mission Authors: Labs, D.; Neckel, H.; Simon, P. C.; Thuillier, G. Bibcode: 1987STIN...8725262L Altcode: Results obtained from the UV-spectrometer of the Solar Spectrum Experiment during the Spacelab 1 mission are presented. The irradiance data concern 492 passbands, which are located between 200 and 358 nm at almost equidistant wavelengths separated by 0.3 nm. The passbands have a well defined, bell-shaped profile with a full width at half maximum of 1.3 nm. The data, which have an error budget between 4% and 5%, agree closely with the spectral distributions observed by Heath (1980) and Mentall et al (1981) and confirm that the solar irradiance and the fluxes of Sun-like stars show the same spectral distribution down to at least 240 nm. Title: The "bright stars" with UBV-colors close to those of the Sun. Authors: Neckel, H. Bibcode: 1986A&A...169..194N Altcode: The paper provides a compilation of the main physical characteristics of all stars included in the "Bright Star Catalogue" (and of four fainter stars), which are quoted to be of luminosity class IVa to Vb and which fulfil one of the following conditions: (1) B-V and U-B are close to the solar values; (2) B-V and spectral type are close to the solar values, while U-B is unknown; (3) the BSC-spectral type is G2 V, but B-V and/or U-B differ appreciably from the solar values. The compilation is given to facilitate the selection of stars which are most suited to serve as a Sun's proxy in the night-sky or which even can be considered as a "solar analog" in as many desired aspects as possible. Title: Absolute magnitudes and luminosity-related physical parameters of the'solar analog' - candidates 16 CYG A and B. Authors: Neckel, H. Bibcode: 1986A&A...167...97N Altcode: Supposing that 16 Cyg A and B are the components of a binary system and therefore have the same age, upper limits of the luminosity can be derived from the conditions that (1) in a luminosity-Teff diagram both stars should lie on or near the same isochrone and (2) the variations of position angle and apparent distance with time and the difference in radial velocity are the result of the orbital motion. Both methods yield maximum distances to 16 Cyg significantly smaller than the distance following from the trigonometric parallax. A differential treatment of the evolutionary tracks of stars with masses around one solar mass yields for the two stars: age between 7 and 9 billion years, absolute visual magnitudes MA ≈ 4m.26, MB ≈ 4m.50 (M_sun; = 4m.82), masses MA ≈ 0.99 M_sun;, MB ≈ 0.96 M_sun;, radii RA ≈ 1.25 R_sun;, RB ≈ 1.15 R_sun;. As a by-product one obtains also the corresponding data for another 'solar analog'-candidate, namely van Bueren 64: age about 0.8 billion years, M64 = 4m.91, M64 ≈ 1.03 M_sun;, R64 ≈ 0.95 R_sun;. Title: The absolute energy distributions of the sun, of the 'solar analogs' 16 CYG B, Hyades VB 64, 16 CYG A and of the standard stars alpha LYR and 29 Psc. Authors: Neckel, H. Bibcode: 1986A&A...159..175N Altcode: The absolute energy distributions of the solar analog 16 Cyg B, which have been published by Hardorp (1980b) and Taylor (1984a), are compared with the Sun's absolute energy distribution by Neckel and Labs (1984). To avoid any passband mismatches, the absolutely calibrated (Neckel and Labs, 1984) version of the high resolution solar flux atlas of Kurucz et al. (1984) was used to derive solar magnitudes for exactly the same passbands that were used for the stellar measurements. The magnitude differences star minus Sun reveal an overall, λ/1-proportional gradient corresponding to Δ(Θ) = Δ(5040/T) ≍ 0.009 ± 0.002, on which is superimposed a wavy pattern with amplitudes being generally near 0.m02. At a few wavelengths one or the other stellar data set - but never both - yields residuals up to 0.m04. Regarding also the differences (a) between observed and model-predicted energy distributions, (b) between 'old' and 'new' energy distribution of α Lyr, and (c) between the energy distributions of different solar analogs, it seems that most if not all of the wavy pattern is caused by systematic, wavelength-dependent errors originating somewhere in the long sequence of observations rather than by genuine characteristics of the stellar or solar radiation. Supposing then that the 'true' 16 Cyg B minus Sun differences run as smoothly as the observed differences between 16 Cyg B and other solar-type stars (e.g. 16 Cyg A), and allowing for remaining errors in the absolute energy distributions involved, the solar UBV-colors should lie within the following limits (see Table 4): (B - V)sun = 0.m650 ± O.m005, (U - B)sun = O.m195 ± O.m005. With VαLyr = 0.m03 and V16CygB = 6.m20 we get Vsun = - 26.m75; its error is presumably less than ± 0.m025. Title: On the absolute energy distributions of the sun, of the "solar analogs" 16 Cyg B, 16 Cyg A, VB 64 and of Vega. Authors: Neckel, H. Bibcode: 1986HiA.....7..863N Altcode: The internal errors and overall accuracy of the disk-center and disk-averaged solar spectra of Neckel and Labs (1984) are analyzed; the absolute solar flux spectrum is compared with the predictions of the Kurucz (1979) model and with the absolute spectra of four solar analogs; and the physical parameters of 16 Cyg A and B are discussed. The results are presented in graphs and tables and characterized. Error waves of amplitude less than 1 percent are found in the spectra of the sun and Vega. Assuming an orbital period of less than 200,000 yr and a radial velocity of about 1 km/s for 16 Cyg A/B, the upper limit of its distance is estimated as 23 pc, corresponding to an absolute magnitude of 4.4 or fainter for 16 Cyg B. Title: Solar line blocking for disk-center and disk-averaged radiation from 3300 to 6860 Å Authors: Neckel, H.; Labs, D. Bibcode: 1985SoPh...95..229N Altcode: The line blocking is tabulated for 10 Å (λ < 6300 Å) or 20 Å (λ > 6300 Å) wide intervals. It follows from the spectral averages and the local continuum derived by Neckel and Labs from high-resolution Fourier transform spectra, which had been obtained by J. Brault at Kitt Peak. The internal accuracy (the scatter) is in the order of 0.1%. Significant systematic errors arising from local distortions of the adopted continuum level can be excluded. Larger errors are to be expected only near the Balmer limit, where the localization of the `continuum' is very ambiguous. Title: On the absolute energy distributions of the Sun, of the "solar analogs" 16 Cyg B, Hyades VB 64, 16 Cyg A, and of the standard stars α Lyr and 29 Psc. Authors: Neckel, H. Bibcode: 1985SSNew...7....4N Altcode: No abstract at ADS Title: High-precision solar radiation data for λλ3300 - 12500 Å. Authors: Neckel, H.; Labs, D. Bibcode: 1985IAUS..111..473N Altcode: No abstract at ADS Title: Recent improvements of the basic solar radiation data for λλ 3300-12500 å Authors: Neckel, H. Bibcode: 1984SSRv...38..187N Altcode: This paper reviews shortly the most reliable observations, which are available at present to describe the basic characteristics of the solar radiation: absolute measurements of the disk-center intensity, high resolution spectra of disk-center intensity and irradiance, and scans of the center to limb variation at continuum wavelengths and for the line-averaged radiation. Further it reports recent results obtained by the merging of these observations, namely high precision data for disk-center intensity and irradiance, which concern not only the line-averaged radiation, but also the position of the continuum. Title: Measurement of the Solar Spectral Irradiance from 200 to 3000 Nanometers Authors: Thuillier, G.; Goutail, J. P.; Simon, P. C.; Pastiels, R.; Labs, D.; Neckel, H. Bibcode: 1984Sci...225..182T Altcode: The solar spectrum experiment on Spacelab 1 measured 98 percent of the sun's total energy output. It improved the absolute accuracy of solar irradiance data, especially in the ultraviolet and infrared regions. In order to detect any variation in the spectrum on future shuttle flights, the data were obtained in a radiation scale that can be preserved with high precision over many years. The instrument performance and preliminary data reduction are described. Title: The solar radiation between 3300 and 12500 Å Authors: Neckel, H.; Labs, D. Bibcode: 1984SoPh...90..205N Altcode: Results are presented, which follow from the merging of: (a) our previously published absolute integrals of the disk-center intensity for 20 Å wide spectral bands; (b) the ratios of mean to central intensity derived from recent observations of the center-to-limb variation of those bands (λ <6600 Å); (c) the ratios of mean to central intensity derived from the observations of the center-to-limb variation at continuum-wavelengths according to Pierce and Slaughter (λ >6600 Å); (d) the high resolution Fourier transform spectra obtained by J. Brault at Kitt Peak for the disk-center and the irradiance; (e) some further auxiliary data, which served mainly to eliminate the local perturbations caused by lines of telluric molecular bands. Title: Erratum - the Solar Radiation Between 3300 and 12500A Authors: Neckel, H.; Labs, D. Bibcode: 1984SoPh...92..391N Altcode: No abstract at ADS Title: Sonnenbeobachtungen vom Raumlabor "Spacelab" aus. Authors: Neckel, H. Bibcode: 1983wuh..conf...27N Altcode: No abstract at ADS Title: An instrument to measure the solar spectrum from 170 to 3200 nm on board Spacelab. Authors: Thuillier, G.; Simon, P. C.; Labs, D.; Pastiels, R.; Neckel, H. Bibcode: 1981SoPh...74..531T Altcode: This instrument, at the present time in development, will fly on board Spacelab I in May 1983. Other flights are foreseen during the following missions. This instrument is composed by three double monochromators covering the range 170 to 3200 nm. The spectrometers have band-passes of 1 nm up to 900 nm and 20 nm from 850 to 3200 nm with an accuracy 10−2 nm. Calibration lamps are included in the instrument to monitor any change of its sensitivity and wavelength scale. Title: An instrument to measure the solar spectrum from 170 to 3200 NM on board Spacelab Authors: Thuillier, G.; Simon, P. C.; Pastiels, R.; Labs, D.; Neckel, H. Bibcode: 1981NASCP2191..165T Altcode: 1981vsc..conf..165T This instrument, at the present time in development, will fly on board Spacelab I in May 1983. Other flights are foreseen during the following missions. The instrument is composed of three double monochromators covering the range 170 to 3200 nm. The spectrometers have bandpasses of 1 nm up to 900 nm and 20 nm from 850 to 3200 nm with an accuracy 1/100 nm. Calibration lamps are included in the instrument to monitor any change of its sensitivity and wavelength scale. Title: Improved Data of Solar Spectral Irradiance from 0.33-MICRONS to 1.25-MICRONS Authors: Neckel, H.; Labs, D. Bibcode: 1981SoPh...74..231N Altcode: The conversion of our centre of disk intensities published in 1968/70 into mean disk intensities has been repeated, using more accurate data for the centre-to-limb variation of both continuous radiation and strong absorption lines. Title: An Instrument to Measure the Solar Spectrum from 170 TO 3200 NM on Board Spacelab Authors: Thuillier, G.; Simon, P. C.; Labs, D.; Pastiels, R.; Neckel, H. Bibcode: 1981sucl.conf..421T Altcode: No abstract at ADS Title: The distribution of masses, ages and luminosities of population I field giants. Authors: Neckel, H. Bibcode: 1975A&A....42..379N Altcode: An attempt is made to obtain an independent semitheoretical estimate of the actual mass, age, and luminosity distributions of stars in the giant region of the HR diagram. An analytical approximation for the mass spectrum of the field giants is derived using the initial luminosity function, the time dependence of the stellar birth rate, and the lifetimes of stars on the main sequence and in the giant region. The predicted mass spectrum is found to exhibit a very pronounced maximum for stars with masses slightly exceeding one solar mass and which were born on the main sequence in the first stages of star formation. The resulting space density is shown to be in close agreement with values deduced from star counts. The predicted magnitude distribution and the predicted position of the field giant branch in the HR diagram are found to agree well with results obtained by recalibrating the Mt. Wilson absolute magnitudes for giants and supergiants using the Wilson-Bappu effect. Title: Helligkeiten und Farben von 1030 frühen M-Sternen in der nördlichen Milchstraße Authors: Neckel, H. Bibcode: 1975MitAG..36..160N Altcode: During the time period from 1967 to 1971 measurements were conducted in Greece and Chile of the brightness and the color of 1030 M2 and M3 stars which are located in a zone along the galactic equator. The zone is 12 deg wide and an area from 6 to 235 deg longitude has been considered. Aspects of interstellar absorption are discussed and attention is given to questions concerning the variability of giant stars. Title: Absolute Helligkeiten und Massen der Sterne des Feldriesenastes Authors: Neckel, H. Bibcode: 1975MitAG..36..166N Altcode: Equations are presented for calculation of the Ca II K emission linewidth, gravitational acceleration, effective temperature, mass, and absolute magnitude of stars in the giant sequence. The time course of these quantities is also evaluated. Results of the present and previous calculations are graphed and analyzed. The emission linewidth is influenced by metal frequency; giants low in metal content are developed stars of relatively small mass which because of their development occur to the right in the main sequence. Low metal frequency thus causes a decrease in linewidth, i.e., leads the star back into the neighborhood of the main sequence. Title: Precision and Consistency of Current Solar Radiation Data Authors: Neckel, H. Bibcode: 1975scea.conf..317N Altcode: No abstract at ADS Title: On a possible generalization of the Wilson-Bappu effect. Authors: Neckel, H. Bibcode: 1974A&A....35...99N Altcode: Summary. A dependence of the Ca ii K line emission width W0 on gravity g and effective temperature Te as suggested by Reimers (1973) for late type stars would imply the following facts: 1. Main sequence stars and stars with horizontal evolutionary tracks in the Mbol - log Te diagram obey strictly a linear relation between log W0 and visual absolute magnitude M ("main sequence relation"). 2. Stars with an upward component (A MboI) of the evolutionary track fall below the main sequence relation by an amount which is 0.33 A Mbol and which corresponds to the systematic deviations to be found in any two-dimensional spectral classification. 3. In the Mv - log W0 diagram the evolutionary tracks of stars, which deviate from the mass-luminosity re lation, are straight lines which are slightly tilted against the main sequence relation. Stars with different masses move along parallel lines. 4. Metal deficiency in old stars with an essentially upward evolution could tend to preserve the main sequence relation. 5 Mv and log W0 fix essentially mass and evolutionary status (namely A Mbot) of single stars, if their metal content is normal or metal deficiency can be accounted for. Key words: Wilson-Bappu effect absolute magnitudes - masses of late type stars Title: Photoelectric catalogue of 1030 BD M-type stars located along the galactic equator. Authors: Neckel, H. Bibcode: 1974A&AS...18..169N Altcode: The majority of the catalogued stars, all of which are of spectral type M2 or M3, have been observed two or more times. Because all stars are potential candidates for being variable, the magnitudes (V) and colours (BV) are given for each individual observation. The mean errors are estimated to be about + 0W()20 in V and + 0T01 5 in B-V 63 stars are known or suspected variables. 128 stars are new variables according to these observations. A crude estimate indicates that about 20 per cent of the M2 stars, and 35 per cent of the M3 stars will show noticeable variations. Some stars with a relatively low colour index may be nearby dwarfs; two stars are suspected to be flare stars. Key words: photoelectric magnitudes - M-type stars Title: Absolute Solar Intensities and the Solar Constant Authors: Neckel, H.; Labs, D. Bibcode: 1973IAUS...54..149N Altcode: No abstract at ADS Title: Intensity of the center of the solar disk in the spectral region 0.33 to 1.25 micron measured from high mountain station Authors: Labs, D.; Neckel, H. Bibcode: 1973srmi.symp..269L Altcode: The method and techniques of absolute radiation measurements are examined. Topics discussed include: calibration procedures; measurement of the intensity of the center of the solar disk vs the mean intensity of the whole disk; high spectral resolution vs a larger bandwidth; and ground-based measurements vs airborne measurements. Measurements of the intensity of the center of the solar disk from a high mountain station are described. Title: Absolute Magnitudes and Colours of Field Giant Branch Stars Authors: Neckel, H.; Klawitter, P. Bibcode: 1973IAUS...54...57N Altcode: No abstract at ADS Title: Proposal for a consistent system of the basic solar radiation data Authors: Neckel, H.; Labs, D. Bibcode: 1973srmi.symp..326N Altcode: The interrelationships between solar radiation data are considered. Consistent solar radiation tables are constructed. The tables are easily compared and checked with both observations and computations of the central disk continuum as well as with observations of the solar irradiance or its integral value, the solar constant. Title: Remarks on the Convergency of Photospheric Model Conceptions and the Solar Quasi Continuum Authors: Labs, Dietrich; Neckel, Heinz Bibcode: 1972SoPh...22...64L Altcode: A comparison is made of the observed intensity in the solar continuous spectrum with those predicted by some models. Arguments are given that the bend-off observed for λ< 0.6 μ is a real phenomenon, and due to a veiled line haze. Title: The Solar Constant (A Compilation of Recent Measurements) Authors: Labs, Dietrich; Neckel, Heinz Bibcode: 1971SoPh...19....3L Altcode: A detailed compilation of the most recent values of the solar constant is given (13 values published from 1967 to 1970). The most probable value seems to be 1.95 cal cm−2 min−1 or 1.36 kW m−2 with a formal rms error of ± 0.3%. The corresponding effective temperature is 5770K. Title: Transformation of the absolute solar radiation data into the `International Practical Temperature Scale of 1968' Authors: Labs, Dietrich; Neckel, Heinz Bibcode: 1970SoPh...15...79L Altcode: Corrections are given which transform the Tables of the solar radiation data (Labs and Neckel, 1968) into the `International Practical Temperature Scale of 1968'. Additionally, for the adjustment of the data of the `true continuum' and the corresponding line blanketing as well, the veiled line effect mentioned first by Carbon et al. (1968), but studied in more detail by Holweger (1970a), has been considered also. Title: The Radiation of the Solar Photosphere from 2000 Å to 100 μm Authors: Labs, D.; Neckel, H. Bibcode: 1968ZA.....69....1L Altcode: No abstract at ADS Title: Die absolute Strahlungsintensität der Mitte der Sonnenscheibe im Spektralbereich 3288 <= λ <= 12480 Å Authors: Labs, D.; Neckel, H. Bibcode: 1967ZA.....65..133L Altcode: No abstract at ADS Title: The use of early M-type stars for determining interstellar absorption Authors: Neckel, H. Bibcode: 1967lts..conf..447N Altcode: No abstract at ADS Title: Die optische Dicke der galaktischen Absorptionsschicht bei Berücksichtigung der Helligkeitsverteilung in den Galaxien. Mit 1 Textabbildung Authors: Neckel, H. Bibcode: 1965ZA.....62..180N Altcode: No abstract at ADS Title: Absolute Intensities of the Center of the Solar Disk in the Spectral Range from 6389 TO 12480. Authors: Labs, A. D.; Neckel, H. Bibcode: 1963ApJ...138..296L Altcode: No abstract at ADS Title: Die absolute Strahlungsintensität der Mitte der Sonnenscheibe im Spektralbereich 6389 >= λ >= 12480 Å. Mit 3 Textabbildungen Authors: Labs, D.; Neckel, H. Bibcode: 1963ZA.....57..283L Altcode: No abstract at ADS Title: Absolute Intensities in the Visible Part of the Solar Spectrum. Authors: Labs, D.; Neckel, H. Bibcode: 1962ApJ...135..969L Altcode: No abstract at ADS Title: Lichtelektrische Infrarot-Farbenindizes Roter Sterne. Mit 4 Textabbildungen Authors: Neckel, H. Bibcode: 1962ZA.....55..166N Altcode: No abstract at ADS Title: Die absolute Strahlungsintensität der Sonnenmitte im Spektralbereich 4010 <= λ <= 6569 Å. Mit 11 Textabbildungen Authors: Labs, D.; Neckel, H. Bibcode: 1962ZA.....55..269L Altcode: No abstract at ADS Title: Approximate Positions of Minor Planets Observed at Heidelberg Authors: Konig, A.; Richter, G.; Neckel, H.; Wenzel, W. Bibcode: 1958MPC...1825...1K Altcode: No abstract at ADS Title: The Distribution of the BD M-Type Stars Along the Galactic Equator. Authors: Neckel, Heinz Bibcode: 1958ApJ...128..510N Altcode: A catalogue is presented containing all BD stars with spectral type M2 or later in a zone 12' wide along the galactic equator While the stars of type MS or later show a rather uniform distribution with galactic longitude, a maximum at t 30' and a minimum at 1 120' is present in the distribution of the stars of type M2-M4, this distribution being similar to that of the Mira-type variables This indicates a concentration of these stars within the local spiral arm. The space density within 430 pc is found to be about 6 X 10-6 pc-3 for the group M2-M4 and about 0 5 X pc-3 for the group MS or later. The average ratio of early to late M's within 1000 pc is 7. Title: A Photographic Observation of the Satellite 1957 Beta leaving the Earth's Shadow Authors: Neckel, Heinz Bibcode: 1958Natur.181..257N Altcode: ON December 15 a photograph of the satellite 1957 Beta was taken at the Warner and Swasey Observatory of the Case Institute of Technology, Cleveland, Ohio, which shows the satellite coming out of the Earth's shadow (Fig. 1). This observation can be used for deriving the distance of the satellite from the Earth's surface. It was concluded from visual observations made the previous morning that the satellite should leave the Earth's shadow in the constellation Ursa Major. An exposure, therefore, was started at 5h. 10m. OOs. E.S.T. with Ursa Major in the centre of the field, although the satellite was not yet visible. The satellite was first observed visually between 5h. 10m. 20s. and 5h. 10m. 30s. It is estimated that it came out of the shadow not earlier than 5h. 10m. 10s. The position where the track is first recorded on the photograph is α = 11h. 53m., δ = + 54.8°. It is possible that the satellite at this position had already left the shadow, but was not recorded earlier because it was at minimum brightness. Nevertheless, since the period of light variation was about 40 sec., the real position should be between the value already given and α = 11h. 37m., δ = + 61°. From these two positions, heights above the surface of 770 and 800 km. respectively were derived, assuming a spherical Earth and a cylindrical shadow with a radius equal to that of the Earth. If refraction isrtaken into account, smaller values of the height result. Assuming a deflexion of the light rays from the Sun of 1°, the corresponding heights are 713 and 739 km. It would appear then that the derived value of 785 +/- 15 km. is a maximum one. From predictions of the Smithsonian Institution a height of about 1,000 km. was expected. According to our observations this is too large by at least 200 km. Title: Die Temperaturverteilung der Sonnenphotosphäre aus Restintensitäten von Fraunhoferlinien. Mit 2 Textabbildungen Authors: Neckel, H. Bibcode: 1958ZA.....44..100N Altcode: No abstract at ADS Title: Die Randverdunklung der Sonne bei 4674 Å und die Temperatureverteilung in den äuβersten Photosphärenschichten. Mit 4 Textabbildungen. Authors: Neckel, H. Bibcode: 1958ZA.....44..153N Altcode: No abstract at ADS Title: Die vertikale Temperaturverteilung in den äußeren Photosphärenschichten der Sonne Title: Die vertikale Temperaturverteilung in den äußeren Photosphärenschichten der Sonne Title: The vertical temperature distribution in the outer photosphere layers of the sun; Authors: Neckel, Heinz Bibcode: 1956PhDT........15N Altcode: No abstract at ADS